Research report Fluoride 52(3 Pt 2):379-384 July 2019 Status of yield characteristics of turnip under fluoride stress Ahmed, Saleemi, Jabeen, Zia, Haider, Syed 379 379 Fluoride 2019 Apr 4. www.fluorideresearch.online/epub/files/029.pdf [Epub ahead of print] STATUS OF YIELD CHARACTERISTICS OF TURNIP (BRASSICA RAPA L.) UNDER FLUORIDE STRESS Shakil Ahmed, a, * Irma Saleemi, a Fareeha Jabeen, a Afia Zia, b Azeem Haider, c S Alam Syed d Lahore, Pakistan ABSTRACT: In this study, an examination was made of the size, fresh weight, and dry weight of turnip, Brassica rapa L., at 70 days after sowing (DAS) when different concentrations of sodium fluoride (NaF) (0 [control], 50 [NaF-50], 100, 150, 200, and 300 [NaF-300] ppm) were applied. The size of the turnip was maximal in the control plants, 20.82 cm 2 . In the plants given NaF-50, as both a soil drench and as a foliar spray, the sizes were 16.32 cm 2 and 18.08 cm 2 , respectively. The size of the turnip gradually decreased as the NaF stress was increased and was at a minimum with NaF-300 for both methods of application (soil drench: 2.47 cm 2 , foliar spray 4.35 cm 2 ). At 70 DAS, the fresh weight was greatest, 66.60 g, in the control plants, followed by 43.06 g, in the plants given NaF-50 by foliar spray. The fresh weight successively declined as the concentration of NaF increased and at NaF-300 and it reached a minimum for both the soil drench, 1.36 g, and the foliar spray, 2.43 g. The dry weight was recorded by oven drying the fresh turnip at 70 DAS, and found to be at a maximum in the control plants, 6.60 g. When a fluoride stress was applied with NaF-50, as a soil drench and a foliar spray, the dry weight decreased to 4.30 g and 5.06 g, respectively. As the concentration of NaF increased, the dry weights decreased in a manner similar to that found with the fresh weights and the lowest values were found with NaF-300 (soil drench: 0.556 g, foliar spray: 1.20 g). In conclusion, NaF applied as both a soil drench and a foliar spray, at concentrations of 50–300 ppm, reduced the size, fresh weight, and dry weight of turnip compared to a control group with 0 ppm NaF. The application of the NaF by soil drench caused a greater degree of stress to the turnip than did the application by foliar spray. Keywords: Brassica rapa L.; Fluoride stress; Pakistan; Turnip; Yield. INTRODUCTION A vast array of environmental hazards are extremely detrimental for plants such as low and high temperature, drought, alkalinity, salinity, UV stress, and pathogen infection. 1 Salt stress with salts, such as fluoride in soil or water, is one of the major stresses, especially in arid and semi-arid regions and can severely limit plant growth and productivity. 2,3 The vegetation is also severely affected by the accumulation of fluoride which can slowly reach alarming concentrations with the passage of time. 4 This increased amount of fluoride in plants can cause various disease including symptoms leaf burning, blackening and yellowing of leaves along with the necrotic spots, and general chlorosis, Fluoride interferes with the phosphorylation of phosphoproteins in cellular membranes 5 and enzymatic activity, 5,6 as well as with the formation of the pigments essential for the phenomena of photosynthesis and various other plant mechanisms. 7,8 Elevated amounts of fluoride in plants have harmful and toxic impacts. The sources of environmental fluoride include various industries, the eruption of volcanoes and the eroding of the materials expelled from them, and the phosphates used in fertilizer industry. 9,10 There are various areas where the soils are naturally enriched with the excessive amounts of fluoride. This natural fluoride can be translocated to the upper parts of the plants by passing through roots a Department of Botany, University of the Punjab, Lahore 54590, Pakistan; b Agricultural Chemistry Department, University of Agriculture, Peshawar, Pakistan; c Institute of Agricultural Sciences, University of the Punjab, Lahore 54590, Pakistan; d Department of Plant Pathology, University of Agriculture, Peshawar. *For correspondence: Shakil Ahmed, Department of Botany, University of the Punjab, Lahore 54590, Pakistan; E-mail: shakil.botany@pu.edu.pk